Surfactant-mediated growth of CoSi2 on Si(100)

Thin co-deposited CoSi₂ films grown at 500–600°C on Si(100) are studied by scanning tunneling microscopy (STM). With a Si rich deposition we observe initially the formation of elongated three-dimensional CoSi₂ islands. The use of one preadsorbed atomic layer of As as a surfactant results in a drastic increase of the island density. This effect appears to be a consequence of a decreased rate of surface diffusion of Co and Si. At higher coverages the roughness of the CoSi₂ film is reduced considerably by the surfactant. The results are discussed with regard to the method of allotaxy which allows the fabrication of buried silicide layers. Here, the requirements for small precipitates and high growth temperature can possibly be met more efficiently using As as a surfactant.